This invention relates to methods and apparatus for generating service detail records, and to monitoring systems for collecting data for these records from a network, such as a packet data network, which is used for example to carry multimedia telephony services as described in the International Telecommunication Union""s commendation H.323 or the Internet Engineering Task Force""s multimedia data and control architecture including the Session Initiation Protocol (SIP). These and similar standards define a set of protocols for establishing sessions or calls which may include one or more users and one or more services, communicating via one or more multimedia channels.
The provision of multimedia communications services over a packet data network (PDN) which may not provide quality of service guarantees has recently generated a great deal of interest due to the success of networks based on the internet protocols (TCP/IP). Network operators are currently trialing multimedia communications services over a variety of packet data networks such as Internet Protocol (IP), Frame Relay (FR) and Asynchronous Transfer Mode (ATM). A major problem is to generate service detail records (generalised call data records), in real-time or batch-mode, which measure the service usage of individual users and the service quality that was actually experienced by the user.
According to one aspect of this invention there is provided a method of generating generalised service detail records for communications (such as telephony) carried over a packet network, comprising the steps of:
acquiring packet network service data from packets carrying the communications;
acquiring signalling data from a signalling protocol to identify at least one of addressing, configuration, statue and timing information for endpoints, gatekeepers and connections involved in a call; and
combining said packet service data and said signalling data to generate service detail records.
According to another aspect of this invention there is provided a method of discovering the network configuration of the endpoints, gatekeepers and their relationships, for a communications service (such as telephony) carried by a PDN, by using a passive monitoring system to capture the signalling messages involved in the configuration and negotiation of relationships, addressing and resource allocation, between endpoints and gatekeepers.
According to a further aspect of this invention there is provided a method of generating generalised service detail records for communications carried over a packet network, comprising the steps of:
acquiring packet network service data for the packets carrying the communications service;
acquiring signalling data regarding at least one of call control, registration, admissions, bandwidth management, call status, address translation and intelligent network services;
acquiring quality of service data for the service transmission level; and
combining said service data, said signalling data and said quality of service data to generate generalised service detail records.
According to another aspect of this invention there is provided a method of monitoring a packet data sub-network (e.g. ethernet segment) or link (e.g. a T3 link carrying IP over a Point-to-Point Protocolxe2x80x94PPP), comprising the steps of: monitoring at a first location signalling messages to detect the existence of a call; and monitoring at multiple other locations to identify some or all packets associated with the call (in H.323, the Call ID can be used to identify all packets associated with a given call). The captured packets may include both signalling data and data from multimedia streams associated with the call. It may be required for wire-tap applications, for example, to use the signalling data to identify calls of interest, and then capture the entire multimedia stream. It may be necessary to buffer captured packets at each location to ensure that all packets associated with the call could be captured.
In addition, the packets associated with a conference call can be correlated together to form a service record for a conference call. This can be achieved by capturing all packets with the same conference ID in H.323, for example.
In some cases it may be desirable to monitor additional signalling messages, e.g. Signalling System No.7 (SS7) protocol messages or Integrated Services Digital Network (ISDN) messages, on signalling links in a switched circuit network (such as the public switched telephone networkxe2x80x94PSTN) coupled to said packet data network, or Media Gateway Control protocol messages (for example MGCP or SGCP) which are used to control the gateway connection between the SCN and the PDN, to derive additional monitoring data, and correlate those additional monitoring data with at least some of first monitoring data. These can be correlated to the original call by using characteristics such as calling or called party numbers to identify the call.
Thus the invention can involve monitoring the control channels used for initiation, modification and termination of multimedia sessions, and may include the monitoring of the multimedia channels themselves, to provide a service detail record for a session.
The invention enables a network operator to generate service detail records on a pure PDN, or on a hybrid network of interconnected PDNs and switched circuit networks SCNs). There is also described a method for automatically discovering the network configuration information, including addressing and identifying the relationships between gatekeepers and endpoints.